Has anyone switched to a smaller tire?

[iznab]

I have a 2014 Ram 2500 6.4 Hemi 3.73 pulling a 30' fifth wheel which weighs approx. 9000lbs. loaded. Stock tire size is 275/70r18. Truck has close to 17k miles and the original Firestone tires need to go. Has anyone switched to a smaller tire? Considering 265/65R18 which would be almost 1.5" smaller diameter. I realize I would have to get a reprogram for speedo but thought it may help towing performance a bit. Overall happy with Hemi but will be doing more towing in the mountains. Any thoughts or suggestions?

[All_I_could_aff]

My revised short answer is no harm will come from slightly smaller, and it should certainly make a small improvement, whether it is enough to be noticeable is hard to say. If for some reason you decide you don’t like the way it looks, it is easily returned to stock either when they wear out, or if u decide to sell them as “lightly used” tires

[Grit_dog]

time2roll wrote:

Grit dog wrote:

time2roll wrote:
I would change gear ratio long before swapping to a smaller tire.
Actually I did go 3.55 to 4.10

Really?

Yes really. Is it that surprising?
Both axles and added TrueTrac differentials about 12 years ago and well worth it.

Totally differnet truck, not even close to the same scenario. An 01 5.4 F150 can use all the help it can get compared to newer gassers. Re gear is a good choice for that truck. Can't get a lot smaller tire comparatively speaking to the 245-70-16 or 17 or whatever they came with.

[Grit_dog]

iznab wrote:
The difference in tire size would theoretically be as effective as re-gearing to a 3.92 ratio according to gear ratio/tire size calculators. I don't think I would spend the money to re-gear. Tire size change wouldn't cost anything extra since I am planning on new tires anyway. Truck sits pretty tall so being 3/4" lower wouldn't hurt my feelings at all. Good point on load capacities. Will have to look at that. Not sure if I would appreciate the look of the smaller tire though. I do appreciate everyone's input. Has anyone actually made this change?

Tires will look a bit small but not ridiculously so. Remember, same truck used to and still comes with 265-70-17s.
It will help for towing power regardless of what the naysayers at and not hurt a thing.

[All_I_could_aff]

I have, but on a wimpy 180 hp Nissan Xterra.
Stock size was 265/70R16. (About 30.5 inches)

I came into a free set of 33 inch tires that I ran for a few months for some off roading. Big loss of power both due to the effect on gearing, and the higher weight.

I then came into a free set of 255/65R16 tires on Pathfinder rims. Definitely felt a difference, even relative to the stock size tires.

[iznab]

The difference in tire size would theoretically be as effective as re-gearing to a 3.92 ratio according to gear ratio/tire size calculators. I don't think I would spend the money to re-gear. Tire size change wouldn't cost anything extra since I am planning on new tires anyway. Truck sits pretty tall so being 3/4" lower wouldn't hurt my feelings at all. Good point on load capacities. Will have to look at that. Not sure if I would appreciate the look of the smaller tire though. I do appreciate everyone's input. Has anyone actually made this change?

[time2roll]

Grit dog wrote:

time2roll wrote:
I would change gear ratio long before swapping to a smaller tire.
Actually I did go 3.55 to 4.10

Really?

Yes really. Is it that surprising?
Both axles and added TrueTrac differentials about 12 years ago and well worth it.

[Grit_dog]

ScottG wrote:
You could do it but be mindful of the new tires capacity. Often (not always) times smaller means less weight carrying.

^ This, but otherwise there is no issue within reason and you don’t need to re cal the speedo for a small change like that. Only thing affected will be the odometer will rack up a few more miles than you’ve driven , in the long term.

[Grit_dog]

time2roll wrote:
I would change gear ratio long before swapping to a smaller tire.
Actually I did go 3.55 to 4.10

Really?

[Durb]

The math shows switching to a 65 series tire would provide 3.3% better acceleration and braking performance. Tire manufacturers will vary. Switching to a 4.10 ratio would be 9.9%.

[time2roll]

I would change gear ratio long before swapping to a smaller tire.
Actually I did go 3.55 to 4.10

[ScottG]

You could do it but be mindful of the new tires capacity. Often (not always) times smaller means less weight carrying.